We're in the process of building an art car, the lighting and some other parts of which are going to be running off a bank of 12V deep cycle batteries (probably four of the standard Costco variety). I'm reasonably familiar with charging such things off a solar setup as I've built a similarly sized setup I use for our camp as well as at home for running lighting.

However with this vehicle there probably won't be enough room to have solar panels that can fully charge the batteries during the day (probably only one ~100W panel), so I'd also like to be able to charge it off the vehicle's alternator and the generator (which should be needed solely for the sound system), but I'm not familiar with what would be needed to charge from all three sources. Can you just connect three separate charge controllers in parallel to the battery bank like this:

It was set up for a 24v charge two batteries.. It was the wrong batteries for the charger.. It made the batteries boil over.. To make sure I put in two farm batteries.. Did the same thing..Put in heavy duty gel and it works fine.. I have a battery guy i go to.. Now I need to know if I can charge the new ones off a DC motor powered by a gas engine... (I have a 24v motor ans a 3hp engine..)

A little inventory of the scrap pile and I found all I will need to make a pusher wheel for the ReTrike.. I have throttle controls but not a thumb type.. It would be safer in this cass..

I'd forget the other chargers and go with the alternator, it'll put out so much more current than the little solar panel or battery charger that they would hardly be worth it. If your engine has room, do what I did and mount a second alternator running in parallel. The original A/C compressor mounts are usually adaptable to hold an alternator.

Or, if you need power when the engine isn't running, use your alternate charging systems then, and switch to the alternator when running the motor.

GreyCoyote: "At this rate it wont be long before he is Admiral Fukkit."Delle: Singularly we may be dysfunctional misfits, but together we're magic.

Captain Goddammit wrote:I'd forget the other chargers and go with the alternator, it'll put out so much more current than the little solar panel or battery charger that they would hardly be worth it. If your engine has room, do what I did and mount a second alternator running in parallel. The original A/C compressor mounts are usually adaptable to hold an alternator.Or, if you need power when the engine isn't running, use your alternate charging systems then, and switch to the alternator when running the motor.

Major plus for this. Switching between charging sources allows you to keep them functionally independent from each other - a huge huge plus. Start adding circuits to combine them in a manner that they can't harm one another, and ignoring cost, complexity and more points of failure, at the minimum you'll be isolating them with a diode or other semiconductor (VFET), and losing some of the voltage that would otherwise be used to charge the battery. The alternator can be done for low bucks too.

Jar Jar Sith Lord.Odd. No bears in the dump. Oh well, lets go across the road & pick blueberries..... but don't harm the red dragon that frequents the area from time to time. He and I have an agreement.

Captain Goddammit wrote:I'd forget the other chargers and go with the alternator, it'll put out so much more current than the little solar panel or battery charger that they would hardly be worth it. If your engine has room, do what I did and mount a second alternator running in parallel. The original A/C compressor mounts are usually adaptable to hold an alternator.

Or, if you need power when the engine isn't running, use your alternate charging systems then, and switch to the alternator when running the motor.

I doubt we'll be able to mount an additional alternator (we actually have alternate plans for the AC compressor).

For charging off an alternator, what sort of system do you use? My quick research indicates that I'll need a battery isolator (along the lines of http://www.amazon.com/NOCO-IGD140HP-Hig ... B001DKRF2M) and possibly some sort of charge controller. However I talked to a friend that has a lot more automotive wrenching experience than I who thinks the charge controller can be skipped, but I don't personally know enough about this yet. I do know that I'm not immediately seeing any reasonably priced controllers on amazon that can handle the current a decent alternator produces.

Your vehicle's alternator will have regulation, either internal or external, that results in an appropriate charging current provided to your vehicle's starting battery. There is no "controller".Assuming your vehicle's starting battery is 12 VDC, if your "bank of 12V deep cycle batteries" is four of them wired in parallel, for a 12VDC bank, then the battery-bank should be able to be wired in parallel to the 12VDC starting battery and both get charged.

But, this means that when the vehicle is not running, any loads running off of the battery-bank is also drawing current from the vehicle's starting battery. You could run it down so far that it will no longer start the vehicle. Hence the use of an isolator. This takes the alternator's charging current and provides it to each "leg", one for the starting battery and another for the battery-bank. Now, with the vehicle off, running loads off of the battery-bank does not draw current from the starting battery - the starting battery is protected and only for the vehicle's use (starting, lights, etc.).

Charging both the starting battery and the battery-bank off the same alternator means that the available charge current is being shared between the starting battery and the battery-bank, therefore the starting battery will charge slower. The battery-bank will likely have a much lower resistance (four batteries in parallel) and will be taking (rudely estimated) 4/5 of the charging current, with the the starting battery getting 1/5 of its usually charge current. If you do a lot of start/stops, you could run the starting battery too low as it isn't getting charged back up after a start as quickly.

What's the vehicle's alternator current?Your vehicle's alternator should be upgradeable to one that provides higher current, so it produces more current for charging both its starting battery and a 12VDC bank of batteries (and running the loads attached to the battery-bank). Hint hint. If you don't go for crazy current (150A, 250A), many vehicles only have 40 to 60 amps, then the cost for an alternator in the 90 amp range can be as low as $45 to $100, or even 120 amps. You can check for what would be a simple upgrade for that vehicle/engine.

You may be able to add yet another bracket, for a second alternator...This would mean your vehicle's starting alternator & battery is electrically independent from the "art systems" alternator & battery bank. No isolator = no charging voltage reduction; so each gets the maximum available charging current from their own alternator.

Three MANUALLY isolated independent charge "modes" for a single alternator and an isolated battery-bank:

Alternator Charging - you further physically isolate the battery-bank with a physical switch between the isolator's "leg" outputs and the battery bank; we'll call it Alternator-to-Battery-Bank swtich. With the Alternator-to-Battery-Bank switch "ON" and the vehicle running, the battery-bank is being charged and that current is available to run "art system" loads (watch for drawing too much current). With the vehicle turned off (so there's no charge current flowing through that swtich), you can physically turn the Alternator-to-Battery-Bank switch "OFF".

Solar Charging - Now, with an independent charge current from solar panels and a solar charge controller, we have another physical switch, "Solar-Charging", that lays between the output of the solar charge controller and the battery-bank. With the Solar-Charging switch on, and Alternator-to-Battery-Bank off, you're solar charging, as per the panel & controller's capabilities.

other charging - With both switches "OFF", you're running your "art systems" off of the battery bank alone. This is also the appropriate switch settings for connecting up a 110VDC battery charger to a generator for charging the battery bank.

Only one switch can be "ON" at one time. You have to make sure this is very clear in the way it is wired up, labeled and people who may touch it are trained.

You need to find someone who is familiar with this type of thing, so it gets wired up correctly, doesn't fry anyone or start a fire.

Have you figured out what voltage the "art systems" lights and "other parts" will be running from?How much current/power they need?How long they can run on four batteries without depleting those batteries below their recommended minimum voltage?

Also, when wiring your batteries together in parallel for a battery-bank, considering using a "star ground" method. This means each negative post gets an equal length of electrical cable that joins to a single point, for providing the negative of the battery-bank. And each positive post gets an equal length of electrical cable that joins it to a single point, for providing the positive connection point of the battery-bank. This means that each battery in the bank will be both charged and discharged equally: same wear & tear on the batteries, and once the charging current is removed, there is no charge loss from current running between the batteries as they try to equalize their charge.

The above is just a place to start. You're going to have to learn this or find someone local who does.

Jar Jar Sith Lord.Odd. No bears in the dump. Oh well, lets go across the road & pick blueberries..... but don't harm the red dragon that frequents the area from time to time. He and I have an agreement.

Canoe wrote:...Hence the use of an isolator. This takes the alternator's charging current and provides it to each "leg", one for the starting battery and another for the battery-bank. ...

Wiring could be that the starting battery and the isolator inputs are wired in parallel, with the isolator providing two charging legs, one of which would go to your battery-bank, and the other unused. CHECK the instructions.

Jar Jar Sith Lord.Odd. No bears in the dump. Oh well, lets go across the road & pick blueberries..... but don't harm the red dragon that frequents the area from time to time. He and I have an agreement.

Canoe wrote:What's the vehicle's alternator current?Your vehicle's alternator should be upgradeable to one that provides higher current, so it produces more current for charging both its starting battery and a 12VDC bank of batteries (and running the loads attached to the battery-bank). Hint hint. If you don't go for crazy current (150A, 250A), many vehicles only have 40 to 60 amps, then the cost for an alternator in the 90 amp range can be as low as $45 to $100, or even 120 amps. You can check for what would be a simple upgrade for that vehicle/engine.

We just replaced the alternator with a 100A model, and have gotten some advice that we switch out the default pulley with a smaller one intended for lower RPMs (such as an art car going at 5mph), but haven't done that yet.

Canoe wrote:Have you figured out what voltage the "art systems" lights and "other parts" will be running from?How much current/power they need?How long they can run on four batteries without depleting those batteries below their recommended minimum voltage?

We're planning for pretty much everything running of 12V, with 12V LED lighting, 12V solenoids and ignitors, plus some Arduino based electronics modules with 5V regulators to step down from the 12V source. We're still estimating what the power requirements are going to be. The biggest draw is going to be around 200ft of RGB LED strip lighting, which maxes out at ~1/3A/ft, or ~66A total, if running all three channels at maximum, but is more likely to be around 20A total most of the time. Plus a couple of high-intensity LEDs for head lights and directional lighting, at most 10A worth. In addition to that we'll be running several 12V solenoids and ignitors for the flame effects, but those are run for very short periods and shouldn't make much of an impact. At a quick estimate I'd say our typical draw will be around 40A, with a max draw around 100A at night. Daytime we'll probably just be running a standard car stereo so there should be plenty of excess power for charging.

The Costco deep cycle batteries are 110AH, so 440AH total, 220AH at 50% discharge. Which would give us around 5 hour operation without any charging current, which is more than enough.

Canoe wrote:Also, when wiring your batteries together in parallel for a battery-bank, considering using a "star ground" method. This means each negative post gets an equal length of electrical cable that joins to a single point, for providing the negative of the battery-bank. And each positive post gets an equal length of electrical cable that joins it to a single point, for providing the positive connection point of the battery-bank. This means that each battery in the bank will be both charged and discharged equally: same wear & tear on the batteries, and once the charging current is removed, there is no charge loss from current running between the batteries as they try to equalize their charge.

Huh, hadn't thought of that. I actually use a full-circle connection (ie controller->battery->battery->...->controller) in my system I use for camp and lighting my basement, but I can see how the equal-wire approach would be a better distribution method.

Canoe wrote:The above is just a place to start. You're going to have to learn this or find someone local who does.

Yeah, I'll be learning it myself. I'm well versed in household wiring and general electronics, and have done some automotive rewiring before, but this is definitely the most complex 12V system I've contemplated working on.

I think the single 100A alternator will be fine, along with that or other suitable isolator.

I'd say switch out that pulley, assuming the vehicle isn't driving itself to the playa. If driving to the playa, switch it out once you get there; only switch it out and back before hand, to be sure you have a belt the right size. Use the proper pulling tool, not a hammer, or else you can bend the shaft or trash the bearings.

Then add the two switches. Allows you to run the three charging modes independently. Or better, there's a Dual Battery Selector switch. Makes it harder to screw up and have the alternator and solar trying to charge at the same time.

Allows 12-24VDC at 150A continuous. Select between "1", "Off" and "2", and unfortunately, "Both". Wire it up as "1" going to the Isolator Leg for alternator charging, and "2" going to the solar charge controller. When at "Off", you can hook up a 110vac battery charger to the battery-bank, powered from a generator.

You need to find a switch that doesn't allow "Both", or modify it so it can't select "Both".This type can be opened through the back by screws.

good selector.jpg

This type wouldn't be good as you have to travel through the settings to get to "Off".

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Jar Jar Sith Lord.Odd. No bears in the dump. Oh well, lets go across the road & pick blueberries..... but don't harm the red dragon that frequents the area from time to time. He and I have an agreement.

I have 3-way charging in my micro-RV. The only scenario you should need to worry about is having the 110v charger and the alternator going at the same time. One of those will have a higher voltage and will try to send current back to the other which may damage something. Or it may be fine depending on the charger, but I wouldn't risk it.

The manual switches listed here are better than the isolator you linked at the start of the thread - you won't lose power through those and it will keep the charging systems separate.

Assuming the solar charger is reasonably smart you should be able to keep it connected straight to the battery all the time. Look in the manual - it should list a voltage where it will automatically shut off. I've had mine that way for over a year with no issues.

I'd avoid using an isolator for the reasons given, they are inefficient. I changed to battery switches on my MV.I'm considering using heavy duty relays to make the system more automatic, so all batteries are in parallel getting charged whenever the engine is running.Remember an alternator's rated output is at higher rpm than it will see while idling on the playa. A smaller pulley will help but they usually come with pretty damn small ones already. There's not much smaller you can go. You can't count on a "100-amp" alternator actually producing that much at idle speed.A second alternator would help a whole lot, I'd try pretty hard to weld up a bracket of some sort if at all possible, but I know sometimes there's just no way. I want a 3rd or even 4th on my rig but the packaging is such that I just can't figure a good way to do it.

GreyCoyote: "At this rate it wont be long before he is Admiral Fukkit."Delle: Singularly we may be dysfunctional misfits, but together we're magic.

Battery IsolatorI agree that manually switching is more efficient (the battery isolator will have a minimum voltage drop of nominal ~.7 VDC across a junction that takes away from the charging voltage). But with a 100A alternator and given the loads, I'm not concerned about that in this case. I do strongly recommend going with a battery isolator in this case. A battery isolator guarantees that the vehicle's Starting Battery cannot be depleted by someone turning on the pretty lights when the usual guardians of the setup aren't present. You do not want to have to deal with a stranded art car. This is a relatively cheap preventative measure.

The isolator must be sized such that it can handle all of the 100A alternator output going to the Starting Battery alone. As I'm sure you're aware, having it sized somewhat higher instead of exactly at 100A is a good idea.

Before tying the various suggestions and ideas together into a robust functioning system, we should consider some points:

The current available in a four parallel 12 VDC battery bank can:

Accidentally, and dramatically, arc weld.

It is willing to try to arc weld you.

The sparks from a short can burn and blind, as can the UV component in the flash.

A wrench or other metallic object falling across the contacts may be partially vaporized and/or launched a surprisingly distance and at a surprising velocity – it won't care that you or someone else is in the way.

The sparks from such are very very good at finding stray fuel and fuel vapour.

When designing the system, we can't know all of the parameters of the various components that may get substituted, either before it hits the playa, or on-playa, to address equipment failure, etc., (this year, or by someone else in a future year).

We cannot guarantee that everyone that may manage to touch the switches understands the consequences of what they select; therefore,

We should have switches wired in a configuration that ensures that there is no combination that can result in damage to any of the components. Benefit due to electrocution safety, fire and 'we get to enjoy our working art car on-playa'.

Solar Charger ProtectionsWhile quality solar chargers will have some degree of self-protection (be it against shorts, polarity or presented with another charging voltage supplied to the battery-bank at the same time), having the solar charger (and other components) isolated through switches ensures any component in the resulting Art Car System cannot be fried by another (protect component (still available, $), electrocution, fire, etc.).

Do ensure that the solar charger can handle panels feeding it voltage while the charger's positive output is not connected to a battery.

If not, a simple solution that allows connection with functional independence, is to add another battery on the solar charger side of the solar switch to meet such a requirement (labelled “optional” in diagram); when Solar is selected with the battery-bank ON, then the battery-bank and this additional battery would all be in parallel.

It may be easier and more economical to use a more robust solar charger; but, it is a benefit to have an additional battery being charged whenever the solar panels are producing a charging current.

Jar Jar Sith Lord.Odd. No bears in the dump. Oh well, lets go across the road & pick blueberries..... but don't harm the red dragon that frequents the area from time to time. He and I have an agreement.

IF SOMETHING GOES WRONG ON-PLAYA, all switches can be set to "OFF" and every component is now isolated from each other.

A Battery-bank Kill Switch (ON/OFF):

removes battery-bank power from the system, and

removes charging current from the battery-bank.

There is a single connection point for all Art Loads (lights, converters, etc.)

Can be routed to a point remote from the Power Selection Box/Panel.

There is a Kill Switch for the Art Load connection – immediately disconnects power (rain short? spilt beer, thrown beer, water balloons, squirt guns, ...). Strictly speaking, this is a redundant switch as power to the art loads can be shut off by selecting Battery-bank OFF and Built-In/External OFF, but that takes both thinking and time, which you may not have.

Should the physical layout of your art car make it prudent, in addition to the kill switch at the power selection box, you can have additional kill switches wired in series. For example: one near the driver/spotter, one at the connection point of the art systems, etc. Have them prominently labelled, such that anyone seeing a need in an emergency can confidently hit it.

Components can be removed/swapped/deleted without having to rewire the setup.

Battery-bank wired with a single “Star” point for the negative and for the positive, with cables of equal length.

Note: the small load of your art systems and the short period of usage on-playa may make a “traditional” “straight bus” connection a 'close enough' second place solution, with the benefit of being both visually neater and cheaper, along with greater ease in inspection on subsequent years before putting it into use. It's not like you're having to squeeze the most life out of a year-round off-the-grid battery-bank.

Each charging/power source can operate functionally isolated from the others.

The External connection terminals can be used for connecting

a battery charger to charge the battery-bank (with Art Loads OFF – most chargers can only charge, not drive loads too), or

the 12VDC output of a generator for running the art loads (Art Loads ON).

If the battery-bank dies on-playa (for whatever reason), turn Battery-Bank to "OFF" and the rest of the components function as normal. Then, if they provide enough power, the art loads may be run off of what you select: Alternator, Solar, External (which can be used to connect the 12 VDC output of a generator that you beg or borrow to throw on the art car).

Last edited by Canoe on Thu Jun 20, 2013 9:52 pm, edited 1 time in total.

Jar Jar Sith Lord.Odd. No bears in the dump. Oh well, lets go across the road & pick blueberries..... but don't harm the red dragon that frequents the area from time to time. He and I have an agreement.

The voltage meter can be in the box/panel, or remote. I've used these with success for various projects. http://www.hobbyking.com/hobbyking/stor ... 150C_.htmlSet the voltage and it will Alarm if the voltage drops below that. Alarm is not very loud, but there's three bright LEDS that flash. There is likely a product available somewhere that is louder.

The diagram does not address where the system or its components may require or be safer with the addition of a fuse or a 12 VDC circuit breaker. If they can be found to handle the appropriate current at a reasonable price, I'd be tempted to put a circuit breaker in series with every positive connection terminal on the resulting Power Selection Box – with most faults they usually react faster than a person looking for a switch to turn off.

This does not address the physical construction, be it cables, connectors, terminals, etc., and the need to shield everything from someone leaning on a connection, or from rain to prevent shorts, etc..

Additionally, batteries need space around them for heat. I have no experience with battery-banks on-playa (except for a simple LiFePO). Check with others to find out what methods have a successful track record.

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Jar Jar Sith Lord.Odd. No bears in the dump. Oh well, lets go across the road & pick blueberries..... but don't harm the red dragon that frequents the area from time to time. He and I have an agreement.

Thanks for all the information above, this discussion has been very useful for my planning purposes. I'm starting to put this system together this week so I'm sure I'll have more questions as the build process moves along...

I'l be running big mobility scooter batteries. So just going with bringing a scooter.. Charge off that.. 24 volts two batteries at a time.. 150 watts top draw.. automatic slow charge.. Hope I never run to low. But six hours from half (12v) to 24.. I try to stay at or above at 18v discharge

Over the weekend I installed most of the charging system based on the above input, using a 200A battery isolator. However I didn't notice the predicted voltage drop, both the starting battery and the deep cycle's appear to be getting 14.5V from the alternator/isolator. The base vehicle is a 1982 Ford Bronco and alternators for these are externally regulated. How I currently have it wired the regulator is getting its current from the isolator rather than the alternator directly, so I suspect the regulator is actually pushing the alternator to produce 14.5+X volts so that the regulator gets that desired 14.5V.

Is this setup likely to do harm to the alternator, or is this a convenient way to get around the isolator's voltage drop on older vehicles?

I'd like to see how you manged to wire that up (four wire regulator?, connecting to stator, field, battery and ground?). You want the alternator feeding its regulator, in turn feeding the isolator. The isolator feeds the starting battery and the battery bank. That way the regulator is in play for charging both.photo or diagram of what you've done?link to your brand & model of isolator so I can get its installation instructions?

p.s. with a 100A alternator the voltage drop (we'll see what it is for your isolator) shouldn't matter. Just means slightly longer to charge, compared to what it would be without the voltage drop. As you're starting with 100A, you're way ahead of the game as you start.

Jar Jar Sith Lord.Odd. No bears in the dump. Oh well, lets go across the road & pick blueberries..... but don't harm the red dragon that frequents the area from time to time. He and I have an agreement.

Canoe wrote:You want the alternator feeding its regulator, in turn feeding the isolator. The isolator feeds the starting battery and the battery bank. That way the regulator is in play for charging both.photo or diagram of what you've done?link to your brand & model of isolator so I can get its installation instructions?

I don't have a photo, but it was previously wired so that the output of the alternator's positive was connected to both the regulator and battery's positive. I moved the alternator's positive output so that it runs direct to the isolator and one of the isolator's output goes to the point where the battery's positive and regulator are joined.

I didn't think at the time to directly measure the output voltage of the alternator while I was working on it this weekend, and probably won't get the opportunity to for another 2-3 weeks as I'm about to be travelling (I just wanted to get this working before leaving so the rest of the crew can start installing the various lighting and accessories while I'm away).

The link takes me to a four pin regulator, which is what we'd expect for that vintage of Ford.

random_vamp wrote:... was previously wired so that the output of the alternator's positive was connected to both the regulator and battery's positive. I moved the alternator's positive output so that it runs direct to the isolator and one of the isolator's output goes to the point where the battery's positive and regulator are joined.

To me this provides unregulated voltage to the battery bank. You'll fry it. You need that regulator in play.

I hope you have installation instructions that come with that. Install it according to their directions.

I can't find any installation instructions at the nocousa web site. But, their Power Products PDF shows a typical installation, which would be taking the stock setup and routing the wire that goes from the alternator to the Starting Battery and re-routing that from that alternator terminal (usually labelled B or Battery) to the isolator input "A". Then the Starting Battery and the Battery Bank each connect separately to the isolator. There may be a particular terminal on the isolator dedicated for a starting battery, as Starting Battery's power is used to excite the alternator when it first starts producing power.

Jar Jar Sith Lord.Odd. No bears in the dump. Oh well, lets go across the road & pick blueberries..... but don't harm the red dragon that frequents the area from time to time. He and I have an agreement.

Canoe wrote:To me this provides unregulated voltage to the battery bank. You'll fry it. You need that regulator in play.

The regulator is definitely in play, with the car running both banks are getting an even 14.5V, without the ~0.7V drop I was led to expect from earlier comments.

Canoe wrote:I hope you have installation instructions that come with that. Install it according to their directions.

It is installed per instructions, however the instructions have nothing regarding external regulators.

Canoe wrote:I can't find any installation instructions at the nocousa web site. But, their Power Products PDF shows a typical installation, which would be taking the stock setup and routing the wire that goes from the alternator to the Starting Battery and re-routing that from that alternator terminal (usually labelled B or Battery) to the isolator input "A". Then the Starting Battery and the Battery Bank each connect separately to the isolator. There may be a particular terminal on the isolator dedicated for a starting battery, as Starting Battery's power is used to excite the alternator when it first starts producing power.

Yeah, that is basically identical to the instructions that came with this one.

I ask the deep cell dealer??? I'll be running 24v (2-12's) deep cell..My 24v charger max 6 amp. times 24 volt = 144 watts..A 300 watt inverter will handle it fine.. At the same time charge AA. AAA, D, 9volt AND C.. The charging system is a 3 hp. engine and an altarnater/w built in reg.. This will charge two 12 volt batt's at 12 volt.. Now I can charge what ever where ever. About a gallon of gas per hour.. Also have a 500 watt gen/w 120 or 12 volt.. Everything above has it's own limit switch and safety over load. Had all the stuff around the house..

Their diagram shows an internally regulated alternator feeding the isolator, which means that the isolator is being fed a regulated voltage. If you want to install it the way they show, then you have to ignore whether the regulator is internal or external, and feed the isolator from the battery attachment point on the alternator, which is the regulated voltage source. It doesn't show modifying an internally regulated alternator and patching a wire to the downside of the isolator feeding the starting battery, which is what your wiring has effectively done. Providing the unregulated VDC to the isolator input and sensing the voltage on the output of the isolator is a really neat way to avoid the voltage drop for the starting battery. But there's more than just the starting battery in play.

That battery attachment point should be the top of the three phase rectifier bridge inside the alternator. When generating power, the regulator should be sensing the voltage at that point and adjusting the excitation coil voltage to regulate the final output. Think classic op-amp. As starting battery charge changes, along with what vehicle electrical accessories are on (lights, etc.), the load changes and (subject to the power limitations of the alternator) the voltage at that attachment point is maintained accordingly.

That the voltage output at both isolator output terminals are the same makes sense. Each terminal should have the same voltage drop and each channel of the isolator circuitry is supplied with the same voltage as it is input to the isolator. You've regulated what that voltage will be, based on the voltage under load of the starting battery. The circuitry of the isolator will either manage or pass through the current draw from the two isolated battery loads. As the charge on the starting battery and the battery bank currently sits, you're looking good with 14.5 volts. Once you've run the battery bank down, you'll be wanting to draw more current to replenish that. Only the regulation of the voltage that will be charging the battery bank, will ignore the charge state and current draw of the battery bank, as it will be based on the voltage regulated to the starting battery, not the combined load that the isolator circuity would normally present (if installed as they show) to the voltage-regulated battery attachment point on the alternator, which would allow the regulator to adjust the alternator output to meet the needs of the combined loads.

If you have the starting battery and battery bank connected to the alternator, and then you turn on the vehicle's headlights, fan, etc., then that extra draw will drop the voltage to the starting-battery/vehicle, which will be sensed and the regulator will try to up the voltage output by the alternator limited by what power it can output. The requirement of the battery-bank is not considered as part of that load; it gets taken along for the ride: it may be undercharged, it may be overcharged. Depending on the circuitry of the isolator, the isolator may be fine with not being able to do its normal job, or something could be damaged by abnormal current flows.

To eliminate on-playa charging-roulette, I would strongly suggest that you leave the regulator wired in as stock, and feed the the isolator from the regulated "battery" attachment point on the alternator.

Jar Jar Sith Lord.Odd. No bears in the dump. Oh well, lets go across the road & pick blueberries..... but don't harm the red dragon that frequents the area from time to time. He and I have an agreement.

Assumptions I think you are making: 12v system voltage. No indication of 12v batteries in series making 24/48v. Right?

I don't see a chart of projected loads and times.

Paralleling a bunch of 12v batteries to build available Amp-Hours. These batteries are unlikely to charge well, in a balanced way.

Not so much discussion of system protection: fuses, breakers, disconnects, protection of connections from horrible Playa dust. Vehicle vibration will make less-than-perfect connections bad. Electrical fire bad.

Use of solid-state battery isolator has a .7v drop. Your alternator (or alternator external field controller) needs a "sense" wire to correct for voltage drop between generator output ann battery input. Not getting the 700mV to the terminal will make a huge charging difference.

OTTOMH, I would use 6v deep cycle batteries in series to make 12v. If you get the charging right, two GC2's will do the trick. Still, GC2's are 65# each, plus mounting box and brackets.

***Solar good in the desert.*** But, it's got to be well-done. Clean/tight connections, short/fat copper wire, good controller programmed right, and most-especially: enough unshaded panel capacity to charge to 85% from however-low you discharge. Or, other strategy is to bulk-charge from a rotary charger (DC-output alternator with external field controller) that is turned by your propulsion engine or a stand-alone prime-mover (tiny engine 3HP Diesel/gas/propane). Worst-case charging (slow, fuel-inefficient) is a portable generator making 120v/60cycle that runs a plug-in charger.